drivers/gnss/serial.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Generic serial GNSS receiver driver
   4  *
   5  * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
   6  */
   7
   8 #include <linux/errno.h>
   9 #include <linux/gnss.h>
  10 #include <linux/init.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/pm.h>
  15 #include <linux/pm_runtime.h>
  16 #include <linux/serdev.h>
  17 #include <linux/slab.h>
  18
  19 #include "serial.h"
  20
  21 static int gnss_serial_open(struct gnss_device *gdev)
  22 {
  23         struct gnss_serial *gserial = gnss_get_drvdata(gdev);
  24         struct serdev_device *serdev = gserial->serdev;
  25         int ret;
  26
  27         ret = serdev_device_open(serdev);
  28         if (ret)
  29                 return ret;
  30
  31         serdev_device_set_baudrate(serdev, gserial->speed);
  32         serdev_device_set_flow_control(serdev, false);
  33
  34         ret = pm_runtime_get_sync(&serdev->dev);
  35         if (ret < 0) {
  36                 pm_runtime_put_noidle(&serdev->dev);
  37                 goto err_close;
  38         }
  39
  40         return 0;
  41
  42 err_close:
  43         serdev_device_close(serdev);
  44
  45         return ret;
  46 }
  47
  48 static void gnss_serial_close(struct gnss_device *gdev)
  49 {
  50         struct gnss_serial *gserial = gnss_get_drvdata(gdev);
  51         struct serdev_device *serdev = gserial->serdev;
  52
  53         serdev_device_close(serdev);
  54
  55         pm_runtime_put(&serdev->dev);
  56 }
  57
  58 static int gnss_serial_write_raw(struct gnss_device *gdev,
  59                 const unsigned char *buf, size_t count)
  60 {
  61         struct gnss_serial *gserial = gnss_get_drvdata(gdev);
  62         struct serdev_device *serdev = gserial->serdev;
  63         int ret;
  64
  65         /* write is only buffered synchronously */
  66         ret = serdev_device_write(serdev, buf, count, 0);
  67         if (ret < 0)
  68                 return ret;
  69
  70         /* FIXME: determine if interrupted? */
  71         serdev_device_wait_until_sent(serdev, 0);
  72
  73         return count;
  74 }
  75
  76 static const struct gnss_operations gnss_serial_gnss_ops = {
  77         .open           = gnss_serial_open,
  78         .close          = gnss_serial_close,
  79         .write_raw      = gnss_serial_write_raw,
  80 };
  81
  82 static int gnss_serial_receive_buf(struct serdev_device *serdev,
  83                                         const unsigned char *buf, size_t count)
  84 {
  85         struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
  86         struct gnss_device *gdev = gserial->gdev;
  87
  88         return gnss_insert_raw(gdev, buf, count);
  89 }
  90
  91 static const struct serdev_device_ops gnss_serial_serdev_ops = {
  92         .receive_buf    = gnss_serial_receive_buf,
  93         .write_wakeup   = serdev_device_write_wakeup,
  94 };
  95
  96 static int gnss_serial_set_power(struct gnss_serial *gserial,
  97                                         enum gnss_serial_pm_state state)
  98 {
  99         if (!gserial->ops || !gserial->ops->set_power)
 100                 return 0;
 101
 102         return gserial->ops->set_power(gserial, state);
 103 }
 104
 105 /*
 106  * FIXME: need to provide subdriver defaults or separate dt parsing from
 107  * allocation.
 108  */
 109 static int gnss_serial_parse_dt(struct serdev_device *serdev)
 110 {
 111         struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
 112         struct device_node *node = serdev->dev.of_node;
 113         u32 speed = 4800;
 114
 115         of_property_read_u32(node, "current-speed", &speed);
 116
 117         gserial->speed = speed;
 118
 119         return 0;
 120 }
 121
 122 struct gnss_serial *gnss_serial_allocate(struct serdev_device *serdev,
 123                                                 size_t data_size)
 124 {
 125         struct gnss_serial *gserial;
 126         struct gnss_device *gdev;
 127         int ret;
 128
 129         gserial = kzalloc(sizeof(*gserial) + data_size, GFP_KERNEL);
 130         if (!gserial)
 131                 return ERR_PTR(-ENOMEM);
 132
 133         gdev = gnss_allocate_device(&serdev->dev);
 134         if (!gdev) {
 135                 ret = -ENOMEM;
 136                 goto err_free_gserial;
 137         }
 138
 139         gdev->ops = &gnss_serial_gnss_ops;
 140         gnss_set_drvdata(gdev, gserial);
 141
 142         gserial->serdev = serdev;
 143         gserial->gdev = gdev;
 144
 145         serdev_device_set_drvdata(serdev, gserial);
 146         serdev_device_set_client_ops(serdev, &gnss_serial_serdev_ops);
 147
 148         ret = gnss_serial_parse_dt(serdev);
 149         if (ret)
 150                 goto err_put_device;
 151
 152         return gserial;
 153
 154 err_put_device:
 155         gnss_put_device(gserial->gdev);
 156 err_free_gserial:
 157         kfree(gserial);
 158
 159         return ERR_PTR(ret);
 160 }
 161 EXPORT_SYMBOL_GPL(gnss_serial_allocate);
 162
 163 void gnss_serial_free(struct gnss_serial *gserial)
 164 {
 165         gnss_put_device(gserial->gdev);
 166         kfree(gserial);
 167 };
 168 EXPORT_SYMBOL_GPL(gnss_serial_free);
 169
 170 int gnss_serial_register(struct gnss_serial *gserial)
 171 {
 172         struct serdev_device *serdev = gserial->serdev;
 173         int ret;
 174
 175         if (IS_ENABLED(CONFIG_PM)) {
 176                 pm_runtime_enable(&serdev->dev);
 177         } else {
 178                 ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
 179                 if (ret < 0)
 180                         return ret;
 181         }
 182
 183         ret = gnss_register_device(gserial->gdev);
 184         if (ret)
 185                 goto err_disable_rpm;
 186
 187         return 0;
 188
 189 err_disable_rpm:
 190         if (IS_ENABLED(CONFIG_PM))
 191                 pm_runtime_disable(&serdev->dev);
 192         else
 193                 gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
 194
 195         return ret;
 196 }
 197 EXPORT_SYMBOL_GPL(gnss_serial_register);
 198
 199 void gnss_serial_deregister(struct gnss_serial *gserial)
 200 {
 201         struct serdev_device *serdev = gserial->serdev;
 202
 203         gnss_deregister_device(gserial->gdev);
 204
 205         if (IS_ENABLED(CONFIG_PM))
 206                 pm_runtime_disable(&serdev->dev);
 207         else
 208                 gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
 209 }
 210 EXPORT_SYMBOL_GPL(gnss_serial_deregister);
 211
 212 #ifdef CONFIG_PM
 213 static int gnss_serial_runtime_suspend(struct device *dev)
 214 {
 215         struct gnss_serial *gserial = dev_get_drvdata(dev);
 216
 217         return gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
 218 }
 219
 220 static int gnss_serial_runtime_resume(struct device *dev)
 221 {
 222         struct gnss_serial *gserial = dev_get_drvdata(dev);
 223
 224         return gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
 225 }
 226 #endif /* CONFIG_PM */
 227
 228 static int gnss_serial_prepare(struct device *dev)
 229 {
 230         if (pm_runtime_suspended(dev))
 231                 return 1;
 232
 233         return 0;
 234 }
 235
 236 #ifdef CONFIG_PM_SLEEP
 237 static int gnss_serial_suspend(struct device *dev)
 238 {
 239         struct gnss_serial *gserial = dev_get_drvdata(dev);
 240         int ret = 0;
 241
 242         /*
 243          * FIXME: serdev currently lacks support for managing the underlying
 244          * device's wakeup settings. A workaround would be to close the serdev
 245          * device here if it is open.
 246          */
 247
 248         if (!pm_runtime_suspended(dev))
 249                 ret = gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
 250
 251         return ret;
 252 }
 253
 254 static int gnss_serial_resume(struct device *dev)
 255 {
 256         struct gnss_serial *gserial = dev_get_drvdata(dev);
 257         int ret = 0;
 258
 259         if (!pm_runtime_suspended(dev))
 260                 ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
 261
 262         return ret;
 263 }
 264 #endif /* CONFIG_PM_SLEEP */
 265
 266 const struct dev_pm_ops gnss_serial_pm_ops = {
 267         .prepare        = gnss_serial_prepare,
 268         SET_SYSTEM_SLEEP_PM_OPS(gnss_serial_suspend, gnss_serial_resume)
 269         SET_RUNTIME_PM_OPS(gnss_serial_runtime_suspend, gnss_serial_runtime_resume, NULL)
 270 };
 271 EXPORT_SYMBOL_GPL(gnss_serial_pm_ops);
 272
 273 MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
 274 MODULE_DESCRIPTION("Generic serial GNSS receiver driver");
 275 MODULE_LICENSE("GPL v2");